More than a billion people live in slums and that figure is growing every day.
Dharavi, in Mumbai, India is Asia's biggest slum.
Mukul Devichand reports from Dharavi on a controversial plan that claims to provide the answer to the developing world's slum problem.
He asks if this audacious scheme is an innovative solution or simply masks a land-grab from the poor.
BBC Radio 4's Crossing Continents was broadcast on Thursday, 14 August, 2008 at 1102 BST. It was repeated on Monday, 18 August, 2008 at 2030 BST.
Reporter: Mukul Devichand
Producer: John Murphy